This project explores the participation rate ("take-up") in Medicaid among non-elderly adults eligible for the program. Millions of uninsured American adults are eligible for public insurance through Medicaid, but are not enrolled. Low take-up is a key policy issue in light of health reform proposals to expand Medicaid eligibility through 133% or 150% of the Federal Poverty Line, and ongoing efforts at the state level to improve health coverage among low-income adults using Medicaid. Previous research has explored poor take-up among children and to a lesser extent among adults, though most published analyses on this topic use data that are nearly a decade old. Furthermore, much is still not known about who chooses to enroll in Medicaid, and what policies affect this choice. This project will provide current estimates of the national and state-specific Medicaid take-up rates among non-elderly adults, and will identify risk factors for low take-up at the individual and state levels. The study will use nationally-representative data from the Current Population Survey (2005- 2009) combined with a comprehensive primary dataset of state Medicaid policies, collected from the published literature and direct contact with Medicaid offices in all 50 states. The study sample will include all non-elderly adults who are eligible for Medicaid and do not have alternative health insurance. Using multivariate logistic regression, and adjusting for demographics and economic conditions, the study will test the relative effects of the following state policies on Medicaid take-up: program enrollment and renewal procedures including waiting periods, interview requirements, and length/complexity of forms;coverage of optional medical services like dental and vision care;use of Medicaid managed care;physician reimbursement rates;and state political ideology. Principal component analysis will be used to consolidate the numerous administrative policies related to Medicaid enrollment and renewal into a single index. Using logistic regression, and controlling for the state and year, the study will also identify what individual characteristics are risk factors for low take-up, such as gender, race, ethnicity, immigration status, level of education, self-reported health status, disability, and presence of Medicaid-eligible children in the home. The goal of this project is to provide greater understanding of how Medicaid can be used to increase health insurance coverage among currently uninsured adults - either through expansions in eligibility, or higher take-up among already eligible individuals. Without such an understanding, one of the key potential tools for improving the health care access and health status of low-income Americans - expanded Medicaid eligibility and enrollment - may be doomed to ineffectiveness due to low take-up. PUBLIC HEALTH RELEVANCE: This project explores why many uninsured adults who are eligible for Medicaid are not enrolled in the program. The study will identify the state policies and individual characteristics that affect enrollment in Medicaid ("take-up") among eligible adults. Understanding the causes of low take-up in Medicaid is critical to effective health care reform and to extending coverage to millions of Americans currently without health insurance.